Hello everyone,
my brother and I are planning to build a semi-detached house, with each of us owning one half. The living space should be approximately 110 sqm (1,184 sq ft) per semi-detached unit and comfortably designed for 1 to 2 people. We each intend to live in our own half but also want to be prepared to rent out or sell one half. We plan to finance separately. We already have a plot of land that can be divided. We aim to achieve at least KFW55 standard, preferably KFW40 or KFW40 Plus with a ground source heat pump (deep drilling), underfloor heating, and controlled ventilation.
Now about our considerations and the knowledge we have gathered so far, without claiming completeness or accuracy. Perhaps some members here have had similar thoughts and can share their knowledge with us 🙂
- Because of the high costs of deep drilling and the heat pump, we are considering using a shared heating system. However, there are several uncertainties here.
- If a shared system requires double the number of boreholes, the savings on drilling may not apply. From boreholes in the nearby area, I know they were drilled up to nearly 200 m (656 ft) deep.
- The heating room must be accessible to both parties, which must also be registered in the land registry. The room must be in the “warm zone” of the building and must not compromise fire protection measures between the two units.
- Operating costs must be billed according to consumption by law, so costs for heating and hot water must be recorded separately for each semi-detached unit. The heat pump needs a separate electricity meter to qualify for a discounted electricity tariff.
- If the heating system is operated “mainly,” meaning more than 50% with renewable energy, a flat-rate billing option is also possible.
- Preferably, the heat pump should be connected to a photovoltaic system. The system must be registered to one of the two parties, or can it be jointly owned and operated?
- Dimensioning the heat pump and the water storage tank: heat pumps are less efficient in the lower operating range, such as during transitional seasons (spring/fall). Could this be more problematic for a larger system?
- Since the two semi-detached units are not fully independent from each other, banks might have issues with separate financing because the two units cannot be sold independently.
We fully understand that a single person may not have answers to all these points, but if anyone who has dealt with some of these topics could share a little input, we would really appreciate it. And please feel free to correct me if any statements are incorrect 🙂
Many thanks in advance and best regards!
my brother and I are planning to build a semi-detached house, with each of us owning one half. The living space should be approximately 110 sqm (1,184 sq ft) per semi-detached unit and comfortably designed for 1 to 2 people. We each intend to live in our own half but also want to be prepared to rent out or sell one half. We plan to finance separately. We already have a plot of land that can be divided. We aim to achieve at least KFW55 standard, preferably KFW40 or KFW40 Plus with a ground source heat pump (deep drilling), underfloor heating, and controlled ventilation.
Now about our considerations and the knowledge we have gathered so far, without claiming completeness or accuracy. Perhaps some members here have had similar thoughts and can share their knowledge with us 🙂
- Because of the high costs of deep drilling and the heat pump, we are considering using a shared heating system. However, there are several uncertainties here.
- If a shared system requires double the number of boreholes, the savings on drilling may not apply. From boreholes in the nearby area, I know they were drilled up to nearly 200 m (656 ft) deep.
- The heating room must be accessible to both parties, which must also be registered in the land registry. The room must be in the “warm zone” of the building and must not compromise fire protection measures between the two units.
- Operating costs must be billed according to consumption by law, so costs for heating and hot water must be recorded separately for each semi-detached unit. The heat pump needs a separate electricity meter to qualify for a discounted electricity tariff.
- If the heating system is operated “mainly,” meaning more than 50% with renewable energy, a flat-rate billing option is also possible.
- Preferably, the heat pump should be connected to a photovoltaic system. The system must be registered to one of the two parties, or can it be jointly owned and operated?
- Dimensioning the heat pump and the water storage tank: heat pumps are less efficient in the lower operating range, such as during transitional seasons (spring/fall). Could this be more problematic for a larger system?
- Since the two semi-detached units are not fully independent from each other, banks might have issues with separate financing because the two units cannot be sold independently.
We fully understand that a single person may not have answers to all these points, but if anyone who has dealt with some of these topics could share a little input, we would really appreciate it. And please feel free to correct me if any statements are incorrect 🙂
Many thanks in advance and best regards!
Hello, our now nearly completed construction project closely matches your description. We also tried to take advantage of the synergies of shared building services, etc. However, all involved experts (notary, architect, building surveyor) advised us to establish a complete technical and legal separation for many reasons, some of which were mentioned above. My brother and I already had separate plots and built two residential units per semi-detached house, with a total of about 300m² (3,230 sq ft) of living space. Even here, selling one or more units after several years remains an option. Easements such as utility rights and access rights lead to complex contractual arrangements. Additionally, the building classification would have changed for us, resulting in different fire protection and soundproofing requirements that would have eliminated earlier cost savings (heat pump).
Such easements often pose an obstacle to future sales. Also, the heat pump turned out to be a relatively small cost factor in the overall budget. Separate arrangements for heat supply are, of course, still possible, but changing the heating curve is rather complicated. Billing becomes unnecessarily complex. The drilling (110m (360 feet) per semi-detached house in our case) ultimately cost about 8,000 (currency) per semi-detached house due to longer excavation work to the technical room.
... the text above is just written down informally, feel free to ask for details about our decision if you wish and if I am able to provide them.
Such easements often pose an obstacle to future sales. Also, the heat pump turned out to be a relatively small cost factor in the overall budget. Separate arrangements for heat supply are, of course, still possible, but changing the heating curve is rather complicated. Billing becomes unnecessarily complex. The drilling (110m (360 feet) per semi-detached house in our case) ultimately cost about 8,000 (currency) per semi-detached house due to longer excavation work to the technical room.
... the text above is just written down informally, feel free to ask for details about our decision if you wish and if I am able to provide them.
Hello everyone,
First of all, many thanks for the very helpful comments; the overall trend is quite clear 🙂
So far, I understand that a shared heat pump in a semi-detached house can lead to various complications, especially concerning the contract, financing, and potential resale.
@i_b_n_a_n Since your situation is very similar to ours, I found your explanations quite accurate. We also had the idea, for sustainability and cost-efficiency reasons, to share as many resources as possible, such as the garden and tools, terrace, waste disposal, internet, photovoltaic system, and of course the heat pump. The difficulties we have encountered ourselves and the additional ones emerging from this discussion make us seriously reconsider this approach.
However, I would like to ask a few more questions @i_b_n_a_n, if that’s okay? You are building two semi-detached houses, each with two residential units. I assume that you plan to live in one unit and rent out the other. That means you supply two residential units with one heat pump each, if I understand correctly? I am interested to know whether you measure the consumption (heating and hot water) of each unit separately and if you plan to bill either a flat rate or based on actual consumption? Also, is there a “main apartment” that covers the joint costs and then allocates them proportionally as additional costs to the “secondary apartment”?
Because a similar model could be possible in our case, where one party takes care of financing, construction, and operation of the photovoltaic system and heat pump and then rents out or carries out a “rent-to-own” agreement with the other party. However, I strongly suspect that this would also involve various problems?
Thanks in advance for your help and best regards!
First of all, many thanks for the very helpful comments; the overall trend is quite clear 🙂
So far, I understand that a shared heat pump in a semi-detached house can lead to various complications, especially concerning the contract, financing, and potential resale.
@i_b_n_a_n Since your situation is very similar to ours, I found your explanations quite accurate. We also had the idea, for sustainability and cost-efficiency reasons, to share as many resources as possible, such as the garden and tools, terrace, waste disposal, internet, photovoltaic system, and of course the heat pump. The difficulties we have encountered ourselves and the additional ones emerging from this discussion make us seriously reconsider this approach.
However, I would like to ask a few more questions @i_b_n_a_n, if that’s okay? You are building two semi-detached houses, each with two residential units. I assume that you plan to live in one unit and rent out the other. That means you supply two residential units with one heat pump each, if I understand correctly? I am interested to know whether you measure the consumption (heating and hot water) of each unit separately and if you plan to bill either a flat rate or based on actual consumption? Also, is there a “main apartment” that covers the joint costs and then allocates them proportionally as additional costs to the “secondary apartment”?
Because a similar model could be possible in our case, where one party takes care of financing, construction, and operation of the photovoltaic system and heat pump and then rents out or carries out a “rent-to-own” agreement with the other party. However, I strongly suspect that this would also involve various problems?
Thanks in advance for your help and best regards!
I have a rather basic question.
We lived in a multi-family building where we owned a condominium unit. The heat source there was also a ground source heat pump. Naturally, both the source (borehole) and the heat pump had to be properly sized. Of course, each unit had its own heating electricity billing.
From my gut feeling, I would assume that a single system serving only two units would be more expensive than two separate systems sized accordingly.
In that sense, wouldn’t the legionella regulations also apply for such a setup? In other words, a temperature of 60°C (140°F)?
That doesn’t seem very efficient either.
We lived in a multi-family building where we owned a condominium unit. The heat source there was also a ground source heat pump. Naturally, both the source (borehole) and the heat pump had to be properly sized. Of course, each unit had its own heating electricity billing.
From my gut feeling, I would assume that a single system serving only two units would be more expensive than two separate systems sized accordingly.
In that sense, wouldn’t the legionella regulations also apply for such a setup? In other words, a temperature of 60°C (140°F)?
That doesn’t seem very efficient either.
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